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Agent skill

Codex Review

by ThibautBaissac in ThibautBaissac/rails_ai_agents

Get an independent second opinion from OpenAI Codex CLI on a plan, diff, spec, or Claude's last response.

MITAuto-check passedEducation

Install Codex Review

skills CLI
$ npx skills add ThibautBaissac/rails_ai_agents --skill codex-review -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI
$ gh skill install ThibautBaissac/rails_ai_agents codex-review --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy
$ git clone --depth 1 https://github.com/ThibautBaissac/rails_ai_agents.git skills-src && mkdir -p .claude/skills && cp -r skills-src/.agents/skills/codex-review .claude/skills/codex-review && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Facts

Skill name
codex-review
GitHub stars
665
Token cost
~1.1k tokens
SKILL.md length
342 words
Files
1
Skills in repo
19
Repo updated
First seen
Licence
MIT

At a glance

Get an independent second opinion from OpenAI Codex CLI on a plan, diff, spec, or Claude's last response.

  • Works in 6 steps: Preflight → Resolve target → Build rubric (skip for diff) → …
  • The user asks to get a second opinion
  • SKILL.md covers 1. Preflight, 2. Resolve target, 3. Build rubric (skip for diff) and 4. Invoke Codex, plus 2 more sections
  • Calls codex; reaches github.com

What it does

Codex Review is an agent skill from ThibautBaissac/rails_ai_agents. Get an independent second opinion from OpenAI Codex CLI on a plan, diff, spec, or Claude's last response. Use when the user asks to "get a second opinion", "have codex review", "cross-check with codex", or wants adversarial review of Claude's output. Argument is one of plan|diff|spec|last-response (default last-response).

Its SKILL.md is about 1.1k tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts.

It sits in Education. The repository describes itself as: Specialized AI skills, agents, rules and hooks for modern Rails AI driven-development + Spec-Driven-Development kit + MCP. The licence is MIT.

When your agent uses it

  • The user asks to get a second opinion
  • Have codex review
  • Cross-check with codex
  • Wants adversarial review of Claudes output

Example prompts

  • “s last response. Use when the user asks to”
  • “have codex review”
  • “cross-check with codex”
  • “/codex-review”

Requirements

  • Pre-approved tools (allowed-tools): Read, Write, Bash(codex *), Bash(command -v *), Bash(ls *), Bash(fd *), Bash(mktemp *), Bash(cat *), Bash(printf *)

Workflow steps

6 steps, taken from the step headings in SKILL.md.

  1. Preflight
  2. Resolve target
  3. Build rubric (skip for diff)
  4. Invoke Codex
  5. Emit review
  6. Ask before reconciling

What it can do on your machine

Read from SKILL.md and the folder at commit 03622f2. It shows what the files ask for, not the result of running them.

  • Tool permissions

    Pre-approves these tools, so the agent can use them without asking each time:

    • Read
    • Write
    • Bash(codex *)
    • Bash(command -v *)
    • Bash(ls *)
    • Bash(fd *)
    • Bash(mktemp *)
    • Bash(cat *)
    • Bash(printf *)

    From allowed-tools in the SKILL.md frontmatter.

  • Runs code

    Shell commands in SKILL.md call:

    • codex

    From the folder's file list and the shell code blocks in SKILL.md.

  • Network

    Hosts in commands or code, which the agent is likely to contact:

    • github.com

    From URLs in SKILL.md, links to its own repository left out.

  • Credentials

    Names no API keys, tokens, secrets or passwords.

    From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Codex Review loads about 1.1k tokens when it runs. Until then it costs about 84 tokens; SKILL.md has 342 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~84
When it runs · the whole SKILL.md, loaded when a task matches
~1.1k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from ThibautBaissac/rails_ai_agents at commit 03622f2, republished under its MIT licence (© ThibautBaissac). 342 words, ~1,054 tokens.

Download SKILL.mdSave it as .claude/skills/codex-review/SKILL.md (or your agent's skills folder).
name
codex-review
description
Get an independent second opinion from OpenAI Codex CLI on a plan, diff, spec, or Claude's last response. Use when the user asks to "get a second opinion", "have codex review", "cross-check with codex", or wants adversarial review of Claude's output. Argument is one of plan|diff|spec|last-response (default last-response).
allowed-tools
Read, Write, Bash(codex *), Bash(command -v *), Bash(ls *), Bash(fd *), Bash(mktemp *), Bash(cat *), Bash(printf *)
argument-hint
[plan|diff|spec|last-response]
user-invocable
true

/codex-review — Independent second opinion from Codex CLI

Argument: $ARGUMENTS — one of plan | diff | spec | last-response. Default last-response.

Never fall back to reviewing Claude's own output if Codex fails. If Codex can't run, say so and stop.

1. Preflight

Run in order. Stop cleanly on first failure:

bash
command -v codex >/dev/null 2>&1 || { echo "codex CLI not found. Install: https://github.com/openai/codex"; exit 0; }
codex login status 2>&1 | grep -qi "logged in" || { echo "codex not logged in. Run: codex login"; exit 0; }

2. Resolve target

  • last-response (default): identify your previous substantive assistant turn (the last turn with user-facing prose — skip turns that are pure tool calls or tool results). Write that prose verbatim to a temp file via the Write tool: $(mktemp -t codex-review).md. Record the path as $TARGET_FILE.
  • plan: if there is an active in-conversation plan, write it to a temp file as above. Otherwise pick the newest file under ./.claude/plans/ (ls -t ./.claude/plans/*.md 2>/dev/null | head -1). If neither exists, report "no plan found" and stop.
  • spec: pick the newest spec.md under ./specs/ (fd -t f 'spec\.md$' ./specs 2>/dev/null | xargs ls -t 2>/dev/null | head -1). If none, stop.
  • diff: no file needed — Codex reads the repo directly via codex review --uncommitted.

3. Build rubric (skip for diff)

The diff target uses codex review's built-in review prompt — do not pass a custom rubric there (--uncommitted is mutually exclusive with [PROMPT] and will error).

For plan | spec | last-response, write this rubric to $(mktemp -t codex-rubric).txt:

You are an adversarial reviewer giving a second opinion. Be terse. Do not restate what is correct.

Check, in order:
1. Correctness — logic errors, off-by-one, wrong APIs, broken invariants.
2. Missing edge cases — nulls, empty inputs, concurrent writes, partial failures, auth gaps.
3. Simpler alternatives — is there a shorter, more conventional, or better-supported approach?
4. Risk — blast radius, reversibility, data loss, security implications.

Output format: 4 sections with those exact headings. Skip a section if you have nothing material. No preamble, no summary, no praise.
Show full SKILL.md (158 more words)Show less

4. Invoke Codex

Use a single Bash call with 600000ms timeout. Capture stdout and exit code. Do not pass -c model=... — rely on the user's ~/.codex/config.toml defaults.

  • diff:
    bash
    codex review --uncommitted
  • plan | spec | last-response:
    bash
    { printf '=== CONTENT TO REVIEW ===\n'; cat "$TARGET_FILE"; printf '\n\n=== REVIEW INSTRUCTIONS ===\n'; cat "$RUBRIC_FILE"; } \
  | codex exec --sandbox read-only --skip-git-repo-check -

Pass all content via stdin. Never put file contents on argv.

5. Emit review

On exit code 0:

### Codex Review

<codex stdout verbatim — no edits, no paraphrase>

On non-zero exit or timeout:

### Codex Review (FAILED)

Codex exited with status <N>. Stderr tail:
<last 20 lines of stderr>

Stop after emitting failure. Do not substitute your own review.

6. Ask before reconciling

After a successful review, end your turn with one question to the user:

Want me to reconcile — decide which points to adopt, reject, or defer?

Only if the user says yes, produce a ### Reconciliation section with three bullet lists: Adopt, Reject (each with a one-line reason), Defer (each with a one-line reason to revisit later). Do not rubber-stamp Codex; reject points that are wrong or off-scope.

© ThibautBaissac, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

Just SKILL.md in .agents/skills/codex-review of ThibautBaissac/rails_ai_agents.

Open the folder on GitHubat commit 03622f2

Compare with similar skills

Codex Review next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Codex Review compared with similar skills
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Codex Review this skillThibautBaissac/rails_ai_agents665—~1.1kAutomated safety check: PassMIT
DeepTutor CLIHKUDS/DeepTutor41k—~2.8kAutomated safety check: PassApache-2.0
AI Engineering Placement Quizrohitg00/ai-engineering-from-scratch66k—~2kAutomated safety check: PassMIT
Deep Reading Analystginobefun/deep-reading-analyst-skill3534 repos~3.6kAutomated safety check: PassMIT
OpenMAIC Setup and ExtensionTHU-MAIC/OpenMAIC40k—~1.7kAutomated safety check: NotesMIT
Codebase to Coursezarazhangrui/codebase-to-course5.7k—~4.4kAutomated safety check: PassNone

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Categories

Questions about Codex Review

What does Codex Review do?

Get an independent second opinion from OpenAI Codex CLI on a plan, diff, spec, or Claude's last response. Codex Review is an agent skill from ThibautBaissac/rails_ai_agents. Get an independent second opinion from OpenAI Codex CLI on a plan, diff, spec, or Claude's last response.

When should I use Codex Review?

Codex Review fits situations like: the user asks to get a second opinion; have codex review; cross-check with codex; wants adversarial review of Claudes output.

How do I install Codex Review in Claude Code?

Run `npx skills add ThibautBaissac/rails_ai_agents --skill codex-review -a claude-code`. Or copy the skill folder (.agents/skills/codex-review in ThibautBaissac/rails_ai_agents) into .claude/skills/codex-review in your project. Claude Code loads it when a task matches its description.

How do I install Codex Review in Codex?

Run `npx skills add ThibautBaissac/rails_ai_agents --skill codex-review -a codex`. Or copy the skill folder (.agents/skills/codex-review in ThibautBaissac/rails_ai_agents) into .agents/skills/codex-review in your project. Codex loads it when a task matches its description.

Can I use Codex Review in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add ThibautBaissac/rails_ai_agents --skill codex-review -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/codex-review, .gemini/skills/codex-review, .github/skills/codex-review and .opencode/skills/codex-review in your project.

What does Codex Review need to run?

Going by SKILL.md and its folder, Codex Review needs the command-line tools its instructions call (codex). Its frontmatter pre-approves these tools: Read, Write, Bash(codex *), Bash(command -v *), Bash(ls *), Bash(fd *), Bash(mktemp *), Bash(cat *), Bash(printf *).

Does Codex Review access the network?

SKILL.md names 1 domain. In commands or code: github.com; the agent is likely to contact it when it follows the instructions. This is read from the text; nothing was executed.

Is Codex Review safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Codex Review use?

Codex Review is published under the MIT licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Codex Review use?

About 1.1k tokens (SKILL.md is roughly 4.2k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.

What are the alternatives to Codex Review?

Skills that share tags, products or a category with Codex Review: DeepTutor CLI (HKUDS/DeepTutor, 41k stars), AI Engineering Placement Quiz (rohitg00/ai-engineering-from-scratch, 66k stars), Deep Reading Analyst (ginobefun/deep-reading-analyst-skill, 353 stars) and OpenMAIC Setup and Extension (THU-MAIC/OpenMAIC, 40k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Codex Review?

ThibautBaissac (a GitHub user) maintains it in ThibautBaissac/rails_ai_agents, which has 665 GitHub stars. The repository holds 19 skills in this directory. The repository was last updated on June 1, 2026.

Source: ThibautBaissac/rails_ai_agents on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.